Influence of treatment efficiency on microbiological stability of water

The declining trend in water demand that has lasted for several dozen years now forces water and sewerage companies to undertake investment activities. These activities are aimed at the mod-ernization of existing water-pipe networks to enhance the guarantee of maintaining the adequate water flow velocities that will ensure the stabilization of the quality of water intended for human consumption. Quite often, an oversizing of a distribution network and hence changes of operating conditions of water distribution network may lead to secondary water contamination making water harmful to human health. The problem of secondary water contamination is particularly important for water supply systems (WSS) that intake raw water from surface reservoirs. In this case, periodic algae and blue-green algae blooming is an issue pose a threat to proper water treatment processes. This article presents the results of the assessment of the effect of the water treatment process on the microbiological stability of water in the WSS, which works on highly eutrophicated surface water resources. An integral element of the analysis is the evaluation of the degree of reduction of indica-tor parameters in-unit water treatment processes, carried out for two variants including the period when drinking water met quality requirements as well as period of bad water quality.